When bulk granular solids, such as aggregates, sugars, salts, chlorine compounds, polymers, or other materials that contain liquid soluble or reactive components are formed, they often tend to stick together. To prevent this sticking, the bulk solids are exposed to a curing atmosphere for several minutes or hours to condition the surface of the granules. This process usually requires storage in a confined space so as to control the curing conditions. A curing vessel is ideal for such curing provided that there is some slight inter-particle motion during the curing time to prevent sticking. A curing vessel is most efficient if the retention time of particles entering the vessel at the same time is about the same for all the particles. Inter-particle motion is difficult to maintain in a batch process, and the most efficient methods use a continuous moving bed process.
Current methods for curing bulk granular solids include belt, vibratory, and screw conveyors, and various mixers such as tumble blenders, rotary cylinders, ribbon blenders, and plow blenders. All these tend to degrade the particles and produce fines. They also have limited low production rates. The most effective, most energy efficient, least particle degrading, high capacity curing vessel is one using continuous gravity flow of a contact bed. Current designs for contact bed gravity flow vessels neglect one or more of the following preferred conditions: (a) bulk solids contact pressure is preferably kept below the crushing pressure for the particles; (b) inter-particle motion between particles preferably occurs sufficiently to keep the particles from sticking; (c) retention time of the vessel is preferably about the same for all the particles; and (d) there are preferably no non-flowing regions in the vessel.
There is a need for a bulk solids curing vessel that can be configured to address these preferred conditions.